Pre-terminated optical cable

ABSTRACT

An optical cable includes a main body and a termination segment extending from an end of the main body. The main body includes middle portions of optical fibers. The termination segment includes end portions of the optical fibers and multi-fiber connectors attached to the end portions of the optical fibers. The multi-fiber connectors are staggered along a length of the termination segment.

TECHNICAL FIELD

The present invention relates generally to optical cables, and, inparticular embodiments, to an optical cable having staggeredpre-terminated fibers.

BACKGROUND

Optical fibers are very small diameter glass strands capable oftransmitting an optical signal over great distances, at very highspeeds, and with relatively low signal loss relative to standard copperwire networks. Optical cables are therefore widely used in long distancecommunication and have replaced other technologies such as satellitecommunication, standard wire communication, etc. Besides long distancecommunication, optical fibers are also used in many applications such asmedicine, aviation, computer data services, etc.

There is a growing need in many applications (e.g., hyperscalecomputing) for optical cables that are able to transfer high data rateswhile taking up minimum space. Such a need may arise in servers wherespace for the optical fiber is a critical limiting factor. Installing ofhigh fiber count cables is very time consuming and expensive because ofthe high number of fiber connections that need to be prepared andspliced/terminated requiring skilled people and specialized equipment.

Optical cables are often installed by pushing, pulling and or blowing inducts. The inner size of the duct determines the maximum diameter of acable that can be installed in a certain duct. Pre-terminated opticalcables are useful for saving time and expense during installation of theoptical cables, but the connectors of pre-terminated optical cables maypresent challenges for installation through ducts.

SUMMARY

In accordance with an embodiment, an optical cable includes: a main bodyincluding middle portions of a plurality of optical fibers, the mainbody having a first outer diameter; and a first termination segmentextending from a first end of the main body, the first terminationsegment having a second outer diameter equal to or smaller than thefirst outer diameter, the second outer diameter being a maximum diameterof the first termination segment through any cross-section of the firsttermination segment along the length of the first termination segment,the first termination segment including: first end portions of theplurality of optical fibers; and a first plurality of multi-fiberconnectors, each multi-fiber connector of the first plurality ofmulti-fiber connectors being attached to respective first end portionsof the plurality of optical fibers, where the first plurality ofmulti-fiber connectors are staggered along a length of the firsttermination segment.

In accordance with another embodiment, an optical cable includes: aplurality of tubes, each of the plurality of tubes including arespective plurality of optical fibers; and a plurality of multi-fiberconnectors, each multi-fiber connector of the plurality of multi-fiberconnectors being attached to an end of a respective tube of theplurality of tubes, the plurality of multi-fiber connectors beingstaggered along a termination segment of the optical cable, thetermination segment being at the end of a main body of the opticalcable, where a largest outer diameter of the termination segment isequal to or smaller than an outer diameter of the main body.

In accordance with yet another embodiment, a method of manufacturing apre-terminated optical cable includes: exposing a plurality of tubes byremoving an outer jacket of an optical cable from a termination segmentof the optical cable, the termination segment extending from a main bodyof the optical cable, the main body having a first outer diameter;setting respective lengths of the plurality of tubes to be staggeredfrom each other; terminating optical fibers of the plurality of tubeswith multi-fiber connectors; and binding the plurality of tubes and themulti-fiber connectors in the termination segment with a wrapper, whereafter binding the plurality of tubes and the multi-fiber connectors, thetermination segment excluding the wrapper has a second diameter, thesecond diameter being the same or smaller than the first diameter.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the disclosure, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIGS. 1A-1C illustrate an optical cable in accordance with anembodiment, wherein

FIG. 1A illustrates a side view of the optical cable, FIG. 1Billustrates a cross-sectional view through a main body of the opticalcable, and FIG. 1C illustrates a cross-sectional view through atermination segment of the optical cable;

FIG. 1D illustrates a cross-sectional view of a tube of an optical cablein accordance with an embodiment;

FIG. 1E illustrates a top view of a flexible ribbon of optical fibers inaccordance with an embodiment;

FIG. 1F illustrates a cross-sectional view of a flexible ribbon ofoptical fibers in accordance with an embodiment;

FIG. 1G is a flow chart of an embodiment method for manufacturing anoptical cable;

FIG. 2 illustrates a side view of the optical cable in accordance withan embodiment; and

FIGS. 3A-3C illustrate a optical cable in accordance with anotherembodiment, wherein FIG. 3A illustrates a side view of the opticalcable, FIG. 3B illustrates a cross-sectional view through a main body ofthe optical cable, and FIG. 3C illustrates a cross-sectional viewthrough a termination segment of the optical cable.

Corresponding numerals and symbols in the different figures generallyrefer to corresponding parts unless otherwise indicated. The figures aredrawn to clearly illustrate the relevant aspects of the embodiments andare not necessarily drawn to scale. The edges of features drawn in thefigures do not necessarily indicate the termination of the extent of thefeature.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of various embodiments are discussed in detailbelow. It should be appreciated, however, that the various embodimentsdescribed herein are applicable in a wide variety of specific contexts.The specific embodiments discussed are merely illustrative of specificways to make and use various embodiments, and should not be construed ina limited scope.

Reference to “an embodiment” or “one embodiment” in the framework of thepresent description is intended to indicate that a particularconfiguration, structure, or characteristic described in relation to theembodiment is included in at least one embodiment. Hence, phrases suchas “in an embodiment” or “in one embodiment” that may be present in oneor more points of the present description do not necessarily refer toone and the same embodiment. Moreover, particular conformations,structures, or characteristics may be combined in any adequate way inone or more embodiments.

The references used herein are provided merely for convenience and hencedo not define the extent of protection or the scope of the embodiments.According to one or more embodiments of the present disclosure, apre-terminated optical cable is provided with a main body including aplurality of optical fibers surrounded by an outer jacket and atermination segment at an end of the main body. The termination segmentincludes pre-terminated optical fibers attached to multi-fiberconnectors. The multi-fiber connectors are arranged in a staggeredpattern around the termination segment so that the outer diameter of thetermination segment is equal to or smaller than the outer diameter ofthe main body. A protection cover that is temporary and removable is putaround the termination segment and the main body for protection of theoptical cable during installation. The protection cover is thin (e.g.,the increase in diameter caused by the temporary wrapper is less than10%) so that it does not contribute much to the additional diameter ofthe optical cable during the installation process, after which it may beremoved. This enables the installation of the optical cable into a sameduct size as intended for an optical cable without attached connectorsor a protection cover.

The outer diameter of the termination segment being equal to or smallerthan the outer diameter of the main body is desirable in order to enablethe installation of pre-terminated optical cables (also referred to aspre-connectorized optical cables) with high optical fiber counts (e.g.,144 to 13824 optical fibers per cable) through ducts suitable foroptical cables without attached connectors. Attaching connectors tooptical cables prior to installation to form pre-terminated opticalcables reduces installation time of the optical cables significantly,Labor costs for installation may be significantly reduced by removingthe time-intensive and skill-intensive step of optical fiber splicingfrom the installation process. For example, terminating the opticalfibers prior to installation will remove the need to splice opticalfibers during installation. Reducing the installation time and necessarylabor skill for installation may remove capital costs that cannot bedeprecated. Because the outer diameter of the termination segment of thepre-terminated optical cable (excluding the temporary protection cover)is equal to or smaller than the outer diameter of the main body, thepre-terminated optical cable may be installed through the same ductsused for unterminated optical cables. As such, existing ducts may beused to install the pre-terminated cable. This meets a significantmarket need for pre-terminated high fiber count optical cables inhyperscale computing that is currently unmet.

FIGS. 1A-1C illustrate an optical cable 100 in accordance with someembodiments. FIG. 1A illustrates a side view of the optical cable 100.FIG. 1B illustrates a cross-sectional view along cross-section 1B-1Bthrough a main body 100A of the optical cable 100 as illustrated in FIG.1A. FIG. 1C illustrates a cross-sectional view along cross-section 1C-1Cthrough a termination segment 100B of the optical cable 100.

Referring first to FIG. 1A, in one or more embodiments, the opticalcable 100 includes a main body 100A and a first termination segment 100B(also referred to as a termination segment 100B) on one or both ends ofthe main body 100A. The termination segment 100B may have a length in arange of 0.5 m to 10 m, such as 5 m.

In some embodiments, the optical cable 100 includes a plurality of tubes112, and each tube 112 of the plurality of tubes 112 includes arespective plurality of optical fibers. The optical fibers may bearranged in flexible ribbons (see below, FIGS. 1D-1F), in flat ribbons,or may be loose fibers. In the main body 100A, the plurality of tubes112 are surrounded by an outer layer 106. In the termination segment100B, the outer layer 106 is removed and the plurality of tubes 112 areexposed. In some embodiments, the optical cable 100 includes a centralstrength member (see below, FIGS. 3A-3C).

In other embodiments, the optical cable 100 is a central tube cable,with a single central tube including a plurality of optical fibers thatmay be arranged in flexible ribbons (see below, FIGS. 1E-1F), in flatribbons, or may be loose fibers. A strength system may surround thecentral tube, such as a layer of strength yarns or strength membersattached to or embedded in the outer sheath of the central tube cable.

Still referring to FIG. 1A, in the termination segment 100B, each tube112 of the plurality of tubes 112 are attached at its respective end toa connector 120 (also referred to as a multi-fiber connector). Theconnector 120 may be any suitable multi-fiber connector. In someembodiments, the connector 120 can terminate a number of optical fibersin a range of 12 to 144, such as 24 optical fibers. The optical fiberscontained in each tube 112 are terminated in the connector 120. Theoptical fibers may subsequently be connected through the connector 120to other optical fibers or data ports during installation in, forexample, a hyperscale computing facility. Although FIG. 1A illustrateseach tube 112 as terminated with a single respective connector 120, itshould be appreciated that this is a non-limiting example. In variousembodiments, two or more tubes 112 may be terminated by singleconnectors 120, or single tubes 112 may include optical fibersterminated by two or more respective connectors 120. The terminationsegment 100B may include a total number of connectors 120 in a range of5 to 500.

As illustrated in FIG. 1A, the connectors 120 are staggered along thelength of the termination segment 100B. For example, in some embodimentsthe connectors 120 are positioned at n axial positions x_(i) (with theindex i running from 1 to n) around the termination segment 100B. Itshould be appreciated that although FIG. 1A illustrates axial positionsx₁ to x₆, the termination segment 100B may extend beyond the rightboundary of FIG. 1A to an axial position x₁ where n is greater than 6.In some embodiments, n is in a range of 10 to 80.

The connectors 120 are arranged at staggered distances from the mainbody 100A in order to keep the diameter of the termination segment 100Bequal to or less than the diameter of the main body 100A. A singleconnector 120 is arranged at the position x₁ (closest to the main body100A) and two or more connectors 120 are arranged at the position x₁(farthest from the main body 100A). As the distance from the main body100A along the termination segment 100B increases, the number of tubes112 decreases due to optical fibers of the tubes 112 being terminated bythe connectors 120. This causes the termination segment 100B to decreasein thickness with increasing distance from the main body 100A. Invarious embodiments, single connectors 120 are arranged at positionscloser to the main body 100A where the termination segment 100B isthicker, and two or more connectors 120 are arranged at positionsfarther from the main body 100A where the termination segment 100B isthinner.

The termination segment 100B is encircled by one or more wrappers 124(also referred to as protective cover(s)) that bind the respectivecomponents of the termination segment 100B (e.g., the plurality of tubes112 and the connectors 120) together. The one or more wrappers 124 holdthe respect components of the termination segment 100B together duringinstallation of the optical cable 100, such as while being pushed,pulled, or blown through a duct. This keeps the footprint of thetermination segment 100B within the footprint of the main body 100A,which is advantageous for installing the optical cable 100 through ductsdesigned to accommodate unterminated optical cables (in other words,optical cables without pre-installed terminating connectors). Thewrappers 124 may be any suitable binding material, such as tape,packaging wrap, plastic twine, braid, mesh, coil, the like, orcombinations thereof. In some embodiments, the wrappers 124 are loops ofpackaging wrap that bind the connectors 120 to the adjacent tubes 112 ofthe termination segment 100B. In some embodiments, the wrappers 124include a spiral of wrapping material (e.g. a plastic strip or twine)around the termination segment 100B. In some embodiments, a singlewrapper 124 is used to cover the entire termination segment 100B, e.g. aprotective sleeve such as a thin plastic sleeve, a non-fray expandablesleeve, flat plastic tubing, adhesive heat shrink, the like, or acombination thereof. The wrapper 124 may further include a pullingsleeve that is applied around the optical cable 100, including a pullingloop at the end of the pulling sleeve in order to facilitate theinstallation of the optical cable 100 through a duct.

The one or more wrappers 124 may have a thickness less than or equal to3 mm, such as in a range of 1 mm to 3 mm, so that the diameter of thetermination segment 100B including the one or more wrappers 124 is nomore than 10% greater than the diameter of the main body 100A withoutthe one or more wrappers 124. In some embodiments, the end of thetermination segment 100B opposite the main body 100A is covered by awrapper 124 (e.g, plastic tubing) that is heat-sealed at the end toprotect the end of the termination segment 100B. The one or morewrappers 124 are temporary and are removed after installation of theoptical cable 100, including any protective sleeve, pulling sleeve, orpulling loop. In some embodiments, a portion of the main body 100Aadjacent to the termination segment 100B is covered by the one or morewrappers 124.

Although not illustrated, the optical cable 100 may further include asecond termination segment 100B on an opposite side of the main body100A from the first termination segment 100B. The second terminationsegment 100B may have optical fibers pre-terminated by connectors 120 asdescribed above with respect to the first termination segment 100B.However, in some embodiments, the connectors 120 are not staggered alongthe length of the second termination segment 100B. This is because thesecond termination segment 100B does not need to be installed through aduct, as only one termination segment of the optical cable 100 (e.g.,the first termination segment 100B) must pass through a duct in mostinstallation procedures.

FIG. 1B illustrates a cross-sectional view along cross-section 1B-1Bthrough the main body 100A of the optical cable 100 as illustrated inFIG. 1A. As shown in FIG. 1B, in the main body 100A, the plurality oftubes 112 is surrounded by an outer layer 106. Although thirty-seventubes are shown in FIG. 1B, this number is not necessarily indicative ofthe total number of tubes 112 that may be included in the optical cable100. For example, the plurality of tubes 112 may include between 6 to 72tubes.

The plurality of tubes 112 fits within an outer layer 106 of the mainbody 100A of the optical cable 100. The outer layer 106 may include anumber of layers such as an outer jacket 118, a water blocking layer108, and an optional strength member (not shown) or strength layer 110.The outer jacket 118 may include polyurethane, polyethylene, nylon, orother suitable material. In one embodiment, the outer jacket 118includes medium-density polyethylene, with a nominal outer jacketthickness of approximately 1 mm, so as to comply with the standards forfiber optic cables such as Telcordia, GR-20 and ICEA-640.Flame-retardant additives may also be included into the outer jacket118. The water blocking layer 108 may include water blocking threads,water blocking tapes, or super absorbent powder type materials.

In some embodiments, the main body 100A has a first diameter D₁ (alsoreferred to as a first outer diameter) across the cross-section 1B-1B ina range of 10 mm to 45 mm, such as 40 mm. This is advantageous so thatthe optical cable 100 can contain a sufficient number of optical fibersfor applications such as hyperscale computing while still being able tobe installed through ducts in computing facilities. The main body 100Ahaving a diameter less than 6 mm may be disadvantageous by notcontaining a sufficient number of optical fibers. The main body 100Ahaving a diameter greater than 60 mm may be disadvantageous by being toowide to be installed through ducts in computing facilities.

FIG. 1C illustrates a cross-sectional view along cross-section 1C-1Cthrough the termination segment 100B of the optical cable 100 asillustrated in FIG. 1A. As an example, the cross-section 1C-1C isthrough a single connector 120 closest to the main body 100A (see above,FIG. 1A). The single connector 120 is bound to the plurality of tubes112 by a wrapper 124. A second diameter D₂ (also referred to as a secondouter diameter) is the maximum diameter of the termination segment 100Bthrough any cross-section of the termination segment 100B along thelength of the termination segment 100B. The second diameter D₂ is equalto or smaller than the first diameter D₁ (see above, FIG. 1B). In someembodiments, the diameter of the termination segment 100B is notconstant along the termination segment 100B, and the termination segment100B is not strictly cylindrical (e.g., due to the straight profiles ofthe connectors 120). As such, the second diameter D₂ is the diameter ofa tight circle circumscribing the termination segment 100B at a positionalong the length of the termination segment 100B where the tight circleis largest (excluding the one or more wrappers 124). As illustrated inFIGS. 1A and 1C, the second diameter D₂ is through the single connector120 closest to the main body 100A along the cross-section 1C-1C, but thesecond diameter D₂ may be through any cross-section of the terminationsegment 100B along the length of the termination segment 100B where thediameter of the termination segment 100B is largest.

In some embodiments, the termination segment 100B has a second diameterD₂ that is equal or greater than the first diameter D₁ of the main body100A, where the second diameter D₂ is the maximum diameter of thetermination segment 100B through any cross-section of the terminationsegment 100B along the length of the termination segment 100B. Forexample, the first diameter D₁ may be 30 mm or smaller and the seconddiameter D₂ may be 30 mm or larger, such as in a range of 30 mm to 40mm. Although the second diameter D₂ may be larger than the firstdiameter D₁, the second diameter D₂ is still small enough to beinstalled through ducts in computing facilities.

In some embodiments, the second diameter D₂ is in a range of 6 mm to 45mm, such as 40 mm. This is advantageous so that the optical cable 100can contain a sufficient number of optical fibers for applications suchas hyperscale computing while still being able to be installed throughducts in computing facilities. The termination segment 100B having adiameter less than 6 mm close may be disadvantageous by not containing asufficient number of optical fibers. The termination segment 100B havinga diameter greater than 60 mm may be disadvantageous by being too wideto be installed through ducts in computing facilities.

The second diameter D₂ being equal to or smaller than the first diameterD₁ is advantageous for installing the optical cable 100, which may havea high optical fiber count (e.g., 3000 or more optical fibers per cable,such as 144 to 10000 optical fibers per cable), through ducts designedto accommodate unterminated optical cables without pre-attachedconnectors. Pre-terminating the optical cable 100 by terminating itsrespective optical fibers with connectors 120 may reduce installationtime of the optical cables significantly, such as from an installationtime of 3 to 5 weeks to an installation time of 3 to 5 days. Labor costsfor installation may be significantly reduced by moving thetime-intensive and skill-intensive step of optical fiber terminationfrom the installation process to the manufacturing process of thepre-terminated optical cable 100. For example, the pre-terminatedoptical cable 100 may not need to have its optical fibers spliced duringinstallation. As such, reducing the installation time and necessarylabor skill for installation may remove capital costs that cannot bedeprecated.

The pre-terminated optical cable 100 may be installed through the sameducts or ducts (e.g., in hyperscale computing facilities) as used forunterminated optical cables with a similar or same number of opticalfibers because the second diameter D₂ of the termination segment 100B ofthe pre-terminated optical cable 100 (including the connectors 120) isequal to or smaller than the first diameter D₁ of the main body 100A.This allows the pre-terminated optical cable 100 to be installed inexisting ducts. The optical cable 100 disclosed herein meets asignificant market need for pre-terminated high fiber count opticalcables (e.g., 6912 optical fiber cables) in hyperscale computing that iscurrently unmet.

While prior art has included pre-terminated optical cables havingconnectors at staggered lengths from the main body of the optical cable,the present disclosure is the first to disclose a termination segment100B of a pre-terminated optical cable 100 having a second diameter D₂being equal to or smaller than a first diameter D₁ of the main body 100Aof the pre-terminated optical cable 100. The prior art does not disclosethis feature. Rather, it shows respective termination segments or theequivalent having wider diameters than the main bodies of the opticalcables. This is disadvantageous because the pre-terminated opticalcables of the prior art cannot be installed through ducts having widthsdesigned to accommodate unterminated optical cables having a same orsimilar number of optical fibers. The pre-terminated optical cable 100of the present disclosure may be installed in the ducts, unlike opticalcables of the prior art.

FIG. 1D illustrates a cross-sectional view of a tube 112 of the opticalcable 100 (see above, FIGS. 1A-1C), in accordance with some embodiments.The tube 112 includes one or more flexible ribbons 125 of optical fibers126 joined together by intermittent bond regions 133 (see below, FIGS.1E-1F) and a tube jacket 115 enclosing the one or more flexible ribbons125. The one or more flexible ribbons 125 run length-wise down the tube112. In one embodiment, the tube 112 may include a single flexibleribbon 125. In other embodiments, the tube 112 may include a pluralityof flexible ribbons 125. In yet other embodiments, the tube 1124 mayinclude a plurality of separate optical fibers not joined in a flexibleribbon 125. In other words, the tube 112 may contain optical fibers freeof bonding material that forms bond regions 133 (see below, FIGS.1E-1F).

In one or more embodiments, the tube jacket 115 may include a flexiblematerial such as flame-retardant polyvinyl chloride (PVC), polypropylene(PP), polyvinylidene fluoride (PVDF), polybutylene terephthalate (PBT),or low smoke zero halogen (LSZH) compounds. In one or more embodiments,the tube jacket 115 may include a deformable material. The wallthickness of the tube jacket 115 is maintained to enable the flexibilityof the one or more flexible ribbons 125 within the tube 112.Advantageously, although the tube jacket 115 may include a flexiblematerial, the use of the tape in various embodiments helps to minimizepressure points on the tube jacket 115 by conforming the flexibleribbons 125 into a near circular shape.

In one or more embodiments, where each of the tubes 112 includes aplurality of flexible ribbons 125, the flexible ribbons 125 may bearranged so that they may be conformed together into a single compactcore of flexible ribbons 125, and then wrapped with finished tape.Alternatively, each of the flexible ribbons 125 within a tube 112 may berolled or folded into individual compact cores without finished tape,and then may be further rolled or folded into a single compact unit orbundle and wrapped with finished tape.

FIG. 1E illustrates a top view of an example flexible ribbon 125 ofoptical fibers 126 and FIG. 1F illustrates a cross-sectional view of theexample flexible ribbon 125 along cross-section 1F-1F as shown in FIG.1E, in accordance with some embodiments. The flexible ribbon 125includes an array of a plurality of optical fibers 126. The plurality ofoptical fibers 126 are arranged as a parallel array such that theflexible ribbon 125 can be arranged in a substantially planar shape, asillustrated in FIG. 1F. As shown in FIG. 1E, the flexible ribbon 125includes a plurality of optical fibers 126 such as the first, thesecond, the third, the fourth, the fifth, and the sixth optical fibers127-132. FIGS. 1E and 1F are not indicative of the total number ofoptical fibers 126 although only six optical fibers are shown. Theflexible ribbon 125 may include any suitable number of optical fibers126. For example, the flexible ribbon 125 may include twelve opticalfibers in one illustration. The optical fibers 126 may have a diameterin a range of 100 microns to 300 microns in various embodiments. Forexample, in one or more embodiments, each optical fiber in a flexibleribbon may have a diameter of 170 to 190 microns, 190 to 210 microns, or235 to 255 microns, such as 18 o microns, 200 microns or 245 microns.

As illustrated in FIGS. 1E and 1F, bond regions 133 are arranged acrossthe flexible ribbon 125 in an intermittent manner to selectively leave alarge surface of the plurality of optical fibers 126 free from thebonding material that forms the bond regions 133. Accordingly, eachoptical fiber is attached to a first neighboring optical fiber throughthe bond regions 133, which do not extend into the second neighboringoptical fiber. Consequently, the plurality of optical fibers 126maintain a large degree of freedom and the flexible ribbon 125 can beeffectively folded or rolled into a compact bundle, resulting in animproved packing density. In addition, the flexible ribbon 125 can beeffectively unfolded and unrolled back into a substantially planarconfiguration, as shown in FIG. 1E, which may be useful for mass fusionsplicing.

In various embodiments, the bond regions 133 may comprise a matrixmaterial acting as the bonding agent between the adjacent optical fibers126. In one embodiment, the matrix material of the bond regions 133 maycomprise an acrylic-based, light-cured instant adhesive, such as a UVcured acrylate material. In another embodiment, the matrix material ofthe bond regions 133 may comprise a cured resin. In alternativeembodiments, the bond regions 133 may comprise other bonding materialssuch as a thermoplastic material.

FIG. 1G illustrates a flow chart of a method 1000 for manufacturing apre-terminated optical cable 100, in accordance with some embodiments.

In step 1002, a plurality of tubes 112 are exposed by removing an outerjacket 118 of the optical cable 100 from a termination segment 10B of anoptical cable. The termination segment 100B extends from a main body 10Aof the optical cable 100 (see above, FIG. 1A). The main body has a firstouter diameter D₁ (see above, FIG. 1B).

In step 1004, respective lengths of the plurality of tubes 112 are setto be staggered from each other.

In step 1006, optical fibers 126 (see above, FIGS. 1E-1F) of theplurality of tubes 122 are terminated with multi-fiber connectors 120(see above, FIG. 1A). In some embodiments, setting respective lengths ofthe plurality of tubes 112 to be staggered from each other includessetting a first tube of the plurality of tubes 112 to a first length,the first length being shorter than the lengths of the remaining tubes112 of the plurality of tubes 112. In some embodiments, settingrespective lengths of the plurality of tubes to be staggered from eachother includes setting a subset of tubes 112 of the plurality of tubes112 to a second length, the second length being greater than the firstlength and greater than the lengths of the remaining tubes 112 of theplurality of tubes 112.

In step 1008, the plurality of tubes 112 and the multi-fiber connectors120 are bound in the termination segment 100B with one or more wrappers124 (see above, FIG. 1A). After binding the plurality of tubes and themulti-fiber connectors, the termination segment has a second diameter D₂(see above, FIG. 1C) that is the same or smaller than the first diameterD₁.

FIG. 2 illustrates a side view of the optical cable 100 after thewrappers 124 are removed from the termination segment 100B, inaccordance with some embodiments. The connectors 120 are attached totubes 112 at staggered lengths from the end of the main body 100A.Although FIG. 2 illustrates each tube 112 as terminated with a singlerespective connector 120, it should be appreciated that this is anon-limiting example. In various embodiments, two or more tubes 112 maybe terminated by single connectors 120, or single tubes 112 may includeoptical fibers terminated by two or more respective connectors 120. Thewrappers 124 may be removed after the optical cable 100 is installedthrough a duct (e.g., in a computing facility) by a suitable method,such as pushing, pulling, or blowing the optical cable 100 through theduct. Once the optical cable 100 is installed through the duct, thewrappers 124 are removed and the various pre-terminated tubes 112 orflexible ribbons 125 of optical fibers 126 (see above, FIGS. 1D-1G) maybe connected through the connectors 120 to suitable connectors locatedin the computing facility.

Embodiments of the present invention are applicable to various types ofoptical cables and are intended to be constrained to a specific type ofoptical cable. Specifically, any type of cable that includes atermination segment may include the embodiments described in thisapplication. This includes not only optical cables but also opticalcables in various embodiments. One such illustration of a optical cable200 is shown in FIGS. 3A and 3B in which a plurality of tubes 112 isformed around a central core.

FIGS. 3A-3C illustrate a different type of optical cable in accordancewith another embodiment of the present disclosure, where the opticalcable includes a central strength member and a plurality of tubesincluding respective pluralities of optical fibers. FIG. 3A illustratesa side view of an optical cable 200 having a central core, FIG. 3Billustrates a cross-sectional view through a main body 200A of theoptical cable 200 along cross-section 3B-3B as illustrated in FIG. 3A,and FIG. 3C illustrates a cross-sectional view through a terminationsegment 200B of the optical cable 200 along cross-section 3C-3C asillustrated in FIG. 3A.

The optical cable 200 is similar to the optical cable 100 as describedabove with respect to FIGS. 1A-2 but also including a central core. Acentral region of the optical cable 200 includes a central strengthmember 202 surrounded by a conventional upjacket 204. The centralstrength member 202 provides mechanical integrity for the optical cable200 when experiencing heavy stress. For example, during installation theoptical cable 200 may be put under significant strain. The centralstrength member 202 is a rigid material and is the primary anti-bucklingelement of the optical cable 200. The central strength member 202resists cable contraction at low temperatures and prevents optical fiberbuckling. The central strength member 202 prevents the optical cable 200from being compressed and provides a primary clamping point for hardwareused to connect to the optical cable 200 for routing enclosures.

The central strength member 202 may include metallic elements, glassreinforced composite rods, aramid reinforced composite rods, orcomposite rods made of some other high modulus, low coefficientexpansion material such as carbon fiber.

In one or more embodiments, the central strength member 202 may beenclosed with an upjacket 204. In other embodiments, the upjacket 204may be a deformable material. The upjacket 204 may include a polymersuch as polypropylene, a material similar to the material of the tubejacket 113 (see above, FIG. 1D), or other polymetric materials such ascellular foam polymer like cellular impact modified nucleatedpolypropylene, for example. The upjacket 204 functions to maintain theproper outer diameter of the central strength member 202 required forthe quantity and size of tubes 112 required for the optical cable 200.The upjacket 204 also functions to assist in maintaining cable rigiditywithin a reasonable range and lowers the overall cost of the opticalcable 200. However, the thickness of the upjacket 204 must be limited toavoid introducing thermal stress onto the central strength member 202.In various embodiments, the diameter of the upjacket 204 may be greaterthan the diameter of the central strength member 202. In one or moreembodiments, the central strength member 202 may not include an upjacket204 because the tubes 112 provide sufficient packing density and relieffrom the built in stress of the optical cable 200.

As illustrated in FIGS. 3A-3C, a plurality of tubes 112 surround thecentral strength member 202 in one or more concentric rows such that thetubes 112 fit within an outer layer 106. Although thirty tubes 112 areshown surrounding the central strength member 202, this is notindicative of the number of tubes 112 that may be included within anoptical cable 200. For example, in one or more embodiments, threeconcentric rows of tubes 112 of equal or unequal quantities may surroundthe central strength member 202. In one or more embodiments, additionalstrength members including the same material as the central strengthmember 202 may be formed concentrically around the central strengthmember 202 between the tubes 112 in any of the concentric rows.

Example embodiments of the disclosure are summarized here. Otherembodiments can also be understood from the entirety of thespecification as well as the claims filed herein.

Example 1. An optical cable including: a main body including middleportions of a plurality of optical fibers, the main body having a firstouter diameter; and a first termination segment extending from a firstend of the main body, the first termination segment having a secondouter diameter equal to or smaller than the first outer diameter, thesecond outer diameter being a maximum diameter of the first terminationsegment through any cross-section of the first termination segment alongthe length of the first termination segment, the first terminationsegment including: first end portions of the plurality of opticalfibers; and a first plurality of multi-fiber connectors, eachmulti-fiber connector of the first plurality of multi-fiber connectorsbeing attached to respective first end portions of the plurality ofoptical fibers, where the first plurality of multi-fiber connectors arestaggered along a length of the first termination segment.

Example 2. The optical cable of example 1, where the first terminationsegment is surrounded by a wrapper.

Example 3. The optical cable of example 2, where the first terminationsegment surrounded by the wrapper has a third outer diameter, the thirdouter diameter being no more than 10% greater than the first outerdiameter.

Example 4. The optical cable of example 1, where the first plurality ofmulti-fiber connectors are arranged at positions distributed along alength of the first termination segment, where a single multi-fiberconnector of the first plurality of multi-fiber connectors is arrangedat a first position closest to the main body, and where two or moremulti-fiber connectors of the plurality of multi-fiber connectors arearranged at a second position farthest from the main body.

Example 5. The optical cable of example 1, where the plurality ofoptical fibers includes more than 3000 optical fibers.

Example 6. The optical cable of example 1, where the first plurality ofmulti-fiber connectors includes 20 or more multi-fiber connectors.

Example 7. The optical cable of example 1, further including a secondtermination segment extending from a second end of the main body, thesecond end being opposite the first end.

Example 8. The optical cable of example 7, where the second terminationsegment has a fourth outer diameter equal to or smaller than the firstouter diameter.

Example 9. The optical cable of example 7, where the second terminationsegment includes a second plurality of multi-fiber connectors, eachmulti-fiber connector of the second plurality of multi-fiber connectorsbeing attached to respective second end portions of the plurality ofoptical fibers.

Example 10. An optical cable including: a plurality of tubes, each ofthe plurality of tubes including a respective plurality of opticalfibers; and a plurality of multi-fiber connectors, each multi-fiberconnector of the plurality of multi-fiber connectors being attached toan end of a respective tube of the plurality of tubes, the plurality ofmulti-fiber connectors being staggered along a termination segment ofthe optical cable, the termination segment being at the end of a mainbody of the optical cable, where a largest outer diameter of thetermination segment is equal to or smaller than an outer diameter of themain body.

Example 11. The optical cable of example 10, where the optical cableincludes a central strength member.

Example 12. The optical cable of example 10, where each respectiveplurality of optical fibers is arranged in one or more ribbons.

Example 13. The optical cable of example 12, where a ribbon of the oneor more ribbons is a flexible ribbon.

Example 14. The optical cable of example 13, where the flexible ribbonincludes intermittent bonds between adjacent optical fibers of theflexible ribbon.

Example 15. The optical cable of example 10, where the plurality ofmulti-fiber connectors includes a subset of multi-fiber connectors, thesubset of multi-fiber connectors being a first distance from the mainbody, the first distance being measured along respective tubes of theplurality of tubes extending between the main body and each multi-fiberconnector of the subset of multi-fiber connectors.

Example 16. The optical cable of example 15, where the remainder of theplurality of multi-fiber connectors besides the subset of multi-fiberconnectors have respective distances from the main body smaller than thefirst distance.

Example 17. The optical cable of example 16, where the respectivedistances from the main body of the remainder of the plurality ofmulti-fiber connectors are different from each other.

Example 18. A method of manufacturing a pre-terminated optical cable,the method including: exposing a plurality of tubes by removing an outerjacket of an optical cable from a termination segment of the opticalcable, the termination segment extending from a main body of the opticalcable, the main body having a first diameter; setting respective lengthsof the plurality of tubes to be staggered from each other; terminatingoptical fibers of the plurality of tubes with multi-fiber connectors;and binding the plurality of tubes and the multi-fiber connectors in thetermination segment with a wrapper, where after binding the plurality oftubes and the multi-fiber connectors, the termination segment excludingthe wrapper has a second diameter, the second diameter being the same orsmaller than the first diameter.

Example 19. The method of example 18, where setting respective lengthsof the plurality of tubes to be staggered from each other includessetting a first tube of the plurality of tubes to a first length, thefirst length being shorter than the lengths of the remaining tubes ofthe plurality of tubes.

Example 20. The method of example 19, where setting respective lengthsof the plurality of tubes to be staggered from each other furtherincludes setting a subset of tubes of the plurality of tubes to a secondlength, the second length being greater than the first length andgreater than the lengths of the remaining tubes of the plurality oftubes.

Example 21. An optical cable including: a main body including middleportions of a plurality of optical fibers; and a first terminationsegment extending from a first end of the main body, the firsttermination segment including: first end portions of the plurality ofoptical fibers; and a first plurality of multi-fiber connectors, eachmulti-fiber connector of the first plurality of multi-fiber connectorsbeing attached to respective first end portions of the plurality ofoptical fibers, where the first plurality of multi-fiber connectors arestaggered along a length of the first termination segment.

While not being restrictive to any one configuration of optical cables,embodiments of the present application may be applied to high densityoptical cables comprising deformable buffer tubes and flexible ribbon,for example, as described in U.S. patent application Ser. No. 16/213,491filed Dec. 7, 2018, Ser. No. 16/028,264 filed Jul. 5, 2018, and Ser. No.17/649,518 filed Jan. 31, 2022, which are all incorporated by referenceherein.

While this invention has been described with reference to illustrativeembodiments, this description is not intended to be construed in alimiting sense. Various modifications and combinations of theillustrative embodiments, as well as other embodiments of the invention,will be apparent to persons skilled in the art upon reference to thedescription. It is therefore intended that the appended claims encompassany such modifications or embodiments.

1. An optical cable comprising: a main body comprising middle portionsof a plurality of optical fibers, the main body having a first outerdiameter; and a first termination segment extending from a first end ofthe main body, the first termination segment having a second outerdiameter equal to or smaller than the first outer diameter, the secondouter diameter being a maximum diameter of the first termination segmentthrough any cross-section of the first termination segment along thelength of the first termination segment, the first termination segmentcomprising: first end portions of the plurality of optical fibers; and afirst plurality of multi-fiber connectors, each multi-fiber connector ofthe first plurality of multi-fiber connectors being attached torespective first end portions of the plurality of optical fibers,wherein the first plurality of multi-fiber connectors are arranged atmultiple angular locations around a central axis and at multiple radialpositions around the central axis, and wherein the first plurality ofmulti-fiber connectors are positioned at multiple locations along alength of the first termination segment.
 2. The optical cable of claim1, wherein the first termination segment is surrounded by a wrapper. 3.The optical cable of claim 2, wherein the first termination segmentsurrounded by the wrapper has a third outer diameter, the third outerdiameter being no more than 10% greater than the first outer diameter.4. The optical cable of claim 1, wherein a single multi-fiber connectorof the first plurality of multi-fiber connectors is arranged at a firstposition closest to the main body, and wherein two or more multi-fiberconnectors of the plurality of multi-fiber connectors are arranged at asecond position farthest from the main body.
 5. The optical cable ofclaim 1, wherein the plurality of optical fibers comprises more than3000 optical fibers.
 6. The optical cable of claim 1, wherein the firstplurality of multi-fiber connectors comprises 20 or more multi-fiberconnectors.
 7. The optical cable of claim 1, further comprising a secondtermination segment extending from a second end of the main body, thesecond end being opposite the first end.
 8. The optical cable of claim7, wherein the second termination segment has a fourth outer diameterequal to or smaller than the first outer diameter.
 9. The optical cableof claim 7, wherein the second termination segment comprises a secondplurality of multi-fiber connectors, each multi-fiber connector of thesecond plurality of multi-fiber connectors being attached to respectivesecond end portions of the plurality of optical fibers.
 10. An opticalcable comprising: a plurality of tubes, each of the plurality of tubescomprising a respective plurality of optical fibers; and a plurality ofmulti-fiber connectors, each multi-fiber connector of the plurality ofmulti-fiber connectors being attached to an end of a respective tube ofthe plurality of tubes, the plurality of multi-fiber connectors beingstaggered along a termination segment of the optical cable, theplurality of multi-fiber connectors being arranged at multiple angularlocations around a central axis and at multiple radial positions aroundthe central axis, and the plurality of multi-fiber connectors beingpositioned at multiple locations along a length of the terminationsegment, the termination segment being at the end of a main body of theoptical cable, wherein a largest outer diameter of the terminationsegment is equal to or smaller than an outer diameter of the main body.11. The optical cable of claim 10, wherein the optical cable comprises acentral strength member.
 12. The optical cable of claim 10, wherein eachrespective plurality of optical fibers is arranged in one or moreribbons.
 13. The optical cable of claim 12, wherein a ribbon of the oneor more ribbons is a flexible ribbon.
 14. The optical cable of claim 13,wherein the flexible ribbon comprises intermittent bonds betweenadjacent optical fibers of the flexible ribbon.
 15. The optical cable ofclaim 10, wherein the plurality of multi-fiber connectors comprises asubset of multi-fiber connectors, the subset of multi-fiber connectorsbeing a first distance from the main body, the first distance beingmeasured along respective tubes of the plurality of tubes extendingbetween the main body and each multi-fiber connector of the subset ofmulti-fiber connectors.
 16. The optical cable of claim 15, wherein theremainder of the plurality of multi-fiber connectors besides the subsetof multi-fiber connectors have respective distances from the main bodysmaller than the first distance.
 17. The optical cable of claim 16,wherein the respective distances from the main body of the remainder ofthe plurality of multi-fiber connectors are different from each other.18. A method of manufacturing a pre-terminated optical cable, the methodcomprising: exposing a plurality of tubes by removing an outer jacket ofan optical cable from a termination segment of the optical cable, thetermination segment extending from a main body of the optical cable, themain body having a first diameter; setting respective lengths of theplurality of tubes to be staggered from each other; terminating opticalfibers of the plurality of tubes with multi-fiber connectors, whereinthe multi-fiber connectors are arranged at multiple angular locationsaround a central axis and at multiple radial positions around thecentral axis, and the multi-fiber connectors are positioned at multiplelocations along a length of the termination segment; and binding theplurality of tubes and the multi-fiber connectors in the terminationsegment with a wrapper, wherein after binding the plurality of tubes andthe multi-fiber connectors, the termination segment excluding thewrapper has a second diameter, the second diameter being the same orsmaller than the first diameter.
 19. The method of claim 18, whereinsetting respective lengths of the plurality of tubes to be staggeredfrom each other comprises setting a first tube of the plurality of tubesto a first length, the first length being shorter than the lengths ofthe remaining tubes of the plurality of tubes.
 20. The method of claim19, wherein setting respective lengths of the plurality of tubes to bestaggered from each other further comprises setting a subset of tubes ofthe plurality of tubes to a second length, the second length beinggreater than the first length and greater than the lengths of theremaining tubes of the plurality of tubes.